Passenger Omar and Jiver fought out an exciting finish to the Graham Hoskin Racegoers Club Handicap Hurdle at Warwick yesterday, but of greater significance to the impartial viewer was the battle taking place for minor honours a dozen or so lengths behind the leaders - the one involving Grand National favourite Clan Royal and Silver Birch, potentially one of the main dangers at Aintree on April 8.

Though neither horse could take advantage of a much lower mark over hurdles, it looked a case of job well done for their respective trainers, Jonjo O'Neill and Paul Nicholls, who are keen to protect the chase ratings of both Clan Royal and Silver Birch before the Grand National weights are unveiled next month.

Willie Mullins executed this plan brilliantly with Hedgehunter in the run up to last year's National, and after yesterday's race Nicholls announced Silver Birch's next outing would be in a chase at Wincanton on February 18 - four days after the National weights are published.

Silver Birch, who was having his first outing since winning the 2004 Coral Welsh National, was given a more aggressive ride than Clan Royal yesterday and helped force the pace until the leaders drew clear in the home straight.

"That was just what we wanted as it's his first serious gallop since he's been back," said Nicholls. Silver Birch remains a general 16-1 chance for the National. Clan Royal, who retains his position as the 8-1 Aintree favourite, was hunted round for the first circuit yesterday by Tony McCoy before easing his way into contention in the final mile. Clan Royal secured third spot by a head without the champion jockey going for everything. "He settled much better today and was more relaxed," reported McCoy. "I was very happy with him and hopefully he'll keep on going the right way."

Tony Martin was the toast of Gowran Park when the well-backed Dun Doire came off the reserves' bench to win the Thyestes Handicap Chase. The seven-year-old only made the cut after Killeaney's late withdrawal. He then had to survive a last-fence blunder to justify 9-4 favouritism under Paul Carberry.

Dun Doire, who has now won six of his last seven races, has a choice of targets at the Cheltenham Festival. "The four-miler was the race for him at the start of the season," said Martin. "We have an amateur of our own called Johnny Farrelly and he would take the ride. The Kim Muir is also a possibility."